quote BT

"Another great plot" is being investigated by the authorities, counter-terrorism minister Lord West has warned.

"There is another great (terrorist) plot building up again and we are monitoring this," he told peers during a debate on new security laws.

Lord West, the former head of the Royal Navy, revealed the existence of the plot as the House of Lords continued debating the Counter Terrorism Bill.

Shadow home secretary Dominic Grieve described Lord West's comments as "reckless in the extreme".

Lord West told peers: "Some of the measures that we have put into place in the past 15 months have made us safer, but that does not mean that we are safe.

"The threat is huge. It dipped slightly and is now rising again within the context of 'severe'. There are large complex plots. We unravelled one, which caused damage to al Qaeda and the plots faded slightly.

"However, another great plot is building up again, which we are monitoring.

"We have done a great deal to protect ourselves and to look after our water supplies, our resilience, underground trains, our preparedness and communications.

"We have done all the things that we need to do, but the threat is building - the complex plots are building."

His warning came less than 24 hours after peers forced the Government to abandon plans to extend maximum pre-charge detention for terror suspects to 42 days.

The Home Office said: "We have always been clear - as has the director general of the Security Service (MI5) - that there are many plots, individuals and groups under investigation. We don't elaborate on specific plots or individuals."

But Conservative MP Patrick Mercer, a member of the Home Affairs Select Committee, told Sky News: "This is an extremely important post... and I hope that Lord West has time to reflect very carefully on his comments and decide whether they were sensible or not."

Sky's foreign affairs editor Tim Marshall says there is some confusion in Whitehall about Lord West's remarks, with one source saying they did not recognise things the way he put them.

The current threat level in the UK is assessed officially as "severe" - the second highest rating